Disclosed in U.S. Pat. No. 3,966,525 issued Jun. 29, 1976 to William L. Steward (the disclosure of which is incorporated herein by reference), is a now commonly employed technique whereby freshly extruded thermoplastic materials are wound onto a rotating mandrel to continuously produce spirally reinforced stretch hose. As the Steward patent explains, a tape-like web of thermoplastic material of substantially uniform width and thickness, and a bead of thermoplastic material of substantially uniform cross-section are extruded concurrently and continuously in a direction toward, and are helically wrapped onto, or wound about, a turning mandrel.
The tacky, freshly extruded thermoplastic materials overlap sufficiently as they are fed onto the rotating mandrel to cause seam-free bonding that produces helically reinforced extensible-retractable stretch hose in a continuous manner. The newly formed hose has a continuous set of helically wound reinforcing coils that are defined by the bead material, with the web material also being helically wound into position bridging between and connecting each adjacent pair of the reinforcing coils. As the mandrel turns, the newly formed stretch hose is caused to rotate as the hose precesses along the mandrel's length. The hose eventually discharges from a distal end region of the mandrel.
Disclosed in the above-referenced U.S. Pat. No. 8,453,681 issued Jun. 4, 2013 to Martin Forrester et al (referred to hereinafter as the Annealing System Patent, the disclosure of which is incorporated herein by reference) is the use of an annealing process that treats discrete lengths of newly produced stretch hose while the discrete lengths are fully axially compressed. Such annealing resets the memory of the thermoplastic material forming the stretch hose, causing discrete lengths of the hose that are stretched or extended, to retract to minimal length when forces causing the hose lengths to extend are released—and causes hose lengths are bent while being stretched, to straighten as they retract toward their minimal axial lengths.
Application Ser. No. 13/507,172 discloses that “stretch hose” formed by continuously wrapping extruded thermoplastic materials about mandrels (that include a plurality of elongate rods which rotate in unison) can be caused to change in cross-sectional dimension (i.e., to increase or to decrease hose diameter) as hose is continuously formed.
Application Ser. No. 13/987,837 —referenced above) discloses that “stretch hose” can be formed continuously by wrapping extruded materials about rotating mandrels, with adjacent pairs of reinforcing coils having their inner diameter regions connected one to the next by thin webs that are sandwiched between the adjacent reinforcing coils when the hose is axially compressed.
None of the several above-referenced documents disclose the production of hose having a web that extends in an inclined spiral from an outer diameter of each reinforcing coil to the inner diameter of an adjacent reinforcing coil, thereby giving the hose something of a thread-like exterior appearance. None of the several documents referenced above discloses a stretch hose having a thin web that advantageously assumes the kind of “double fold” that occurs when hose embodying the preferred practice of the present invention is axially compressed.